In particular, the present invention is related to a weighing device (or ‘scale’), especially a weighing device suitable for personal use (weighing an individual). The weighing device employs at least four inductive sensors for detecting small variations in vertical motion of a plate of the weighing device.
US2010/0133016 discloses a scale having a base plate and a load plate located at a distance above the base plate for supporting an object to be weighed. Between the base plate and the load plate there are provided four spacing elements at the corners and the scale comprises four centrally arranged inductive sensors determining changes in distance between the base plate and the bed plate.
However, it turns out that errors may occur in such weighing devices when a load to be weighed is placed in an off-center position, or in particular if the elastic properties of the spacing elements are different from one another because of manufacturing deviation or other reason.
Moreover, in the known art, the flexibility of the top plate can be detrimental to the measurement accuracy, because as it flexes, the measured travel of the top plate at the sensing elements versus the travel of the top plate at the spacing elements are somewhat unrelated or at least uncertain.
Therefore it remains a need for improved weighing devices, which exhibit high accuracy and small thickness.